Occupancy sensors are known for sensing occupancy within a designated area and for activating an electrical load or system in response to sensing a person(s) within the designated area. The occupancy sensor can be connected to a load such as a lighting device or system, heating, ventilation and air conditioning (HVAC) system or other electrical system that is intended to be activated only when needed. The sensor device within the occupancy sensor can be an infrared detector and/or an ultrasonic detector, for example, that is capable of detecting when the designated area is occupied by a person or moving object. The occupancy sensor is typically mounted on a wall or ceiling and positioned so that the field of view of the occupancy sensor covers the designated area.
Occupancy sensors are typically used to reduce the energy consumption required for illuminating a target area or otherwise operating an environmental load device such as an HVAC system. The occupancy sensors require reliable activation when the target area is occupied and prevention of false activations when the area is vacant. Various occupancy sensors have been developed with an attempt to improve the reliability of the sensors. One example is disclosed in U.S. Pat. No. 7,411,489 to Elwell et al. which discloses an occupancy sensor that is able to maintain activation when sensing continuing occupancy. The occupancy sensor also includes component settings to enable self-adjusting of the settings. The occupancy sensor is activated upon sensing continuing occupancy and enables separate processing of the settings. An ultrasonic sensor is included to actively sense occupancy and to enable separate processing of the settings. The occupancy sensor is activated when the infrared sensor section senses occupancy and maintains activation when either the infrared sensor or the ultrasonic sensor senses continuing occupancy. U.S. Pat. No. 6,415,205 to Myron et al. relates to ultrasonic infrared sensors used to produce first and second occupancy estimator signals. The estimator signal is used to switch electrical loads when the estimator signals are above a predetermined threshold. The occupancy sensor is intended to provide high probability of occupancy detection and low probability of false tripping.
Various occupancy sensors have been developed with an attempt to improve the housings of the sensors. For example, U.S. Patent Publication No. 2007/0229297 to Leonard et al. relates to an occupancy sensor powerbase with a housing in a low voltage wiring terminating unit terminal block. A power pack is connected to the low voltage terminal block with upper lower portions combined to form an integral power stand alone sensor unit.
Various occupancy sensors have been developed with an attempt to improve the lenses of the sensors. For example, U.S. Pat. No. 6,215,398 to Platner et al. discloses an occupancy sensor with flat lenses for focusing detecting beams into narrow long range beams. The sensing circuit generates a detecting beam that is substantially perpendicular to the lens. The lens has a plurality of lens segments to provide long, intermediate and short range sensing beams. An override timer circuit is provided which upon activation sets the occupancy sensor in occupancy mode for a predetermined period of time.
A number of occupancy sensors are available which have photo sensors for detecting ambient light and selectively disabling an electrical load from being powered on in response to occupancy detection because ambient light conditions are above a selected threshold, thereby reducing energy consumption. For example, U.S. Pat. No. 5,699,243 to Eckel et al discloses a motion sensing system having a photosensor and programmed ambient light level control.
A need exists in the industry for an occupancy sensor to provide fixture override control, that is, selective control of lighting fixture light output and lamp switching. Some current lighting fixtures are equipped with multiple light level option wiring connections. This is sometimes accomplished by having more than one ballast in the fixture. There are also systems that provide multiple inputs to a single ballast to control the light output of the fixture. Either configuration allows the fixture to be operated to offer more light levels than just fully energized and de-energized. For example, it may be desirable to selectively disable or alter the operation of an occupancy sensor that, under normal operating conditions, would suspend activation of an electrical system, or lower the light output of a lighting fixture, when ambient light conditions are above a selected threshold. A situation wherein disabling of the photocell operation of an occupancy sensor is desired may be when an occupancy sensor and associated lighting load is located near a skylight. Further, it may be desirable to disable a selected subset of a group of fixtures connected to corresponding occupancy sensors. Thus, a need exists for disabling or altering the operation of the occupancy sensor operating as a load controller to allow the flexibility of overriding the lighting to a higher or lower level than set by the photocell threshold. This would allow the system to respond to load shedding requests or to the desires of the occupants.
In previous products, there was no way to add fixture override control to an existing installation, if the original controller was not purchased with a class II control connector, without replacing the existing controller. It is disadvantageous, however, to provide a connector for fixture override control on the housing of such an occupancy sensor for a number of reasons. For example, such a connector would increase labor because Underwriter Laboratories, Inc. standards require a high potential test between any connector and any Class 1 wire in such an occupancy sensor. An additional wire connector also increases cost of the occupancy sensor, provides another inlet for dust and contaminants to enter the sensor housing, and increases the possibility of wiring mistakes in the field. Further, more SKUs are needed for the sensor family (e.g., sensors with the override connector having different SKUs than sensors without the override connector), adding to the cost and complexity of marketing and inventory management.
A need therefore exists for an override control system for an occupancy sensor that does not require a separate wire connector to the occupancy sensor.